Introduction

Many independent schools face a dilemma with their swimming pools. Existing water  treatment regimes are often hopelessly antiquated, without any sort of automatic chlorine dosing system in place. (Images of a trusty janitor with a bucket of sodium hypochlorite spring to mind). Very few of these pools switched to ozone when it became available (as many municipal pools did) as it was simply too expensive.

Despite this lack of investment – or perhaps because of it – pool operating costs are spiralling, meaning many independent schools are having to open up their pools to the general public to generate extra income. This means higher bather loads than existing treatment systems can often cope with. Combined chlorine levels start to go up (especially if children or elderly people use the pool), requiring more chlorine dosing, which in turn requires more dilution, backwashing and water disposal – another major expense.

All these factors have been driving many independent schools to seriously consider shutting down their pools – not because they want to but because they feel they can no longer afford to keep them operational. So what is the solution?

UV treatment – the panacea?

UV is now a well established method of water treatment for indoor municipal pools – in fact, it is often the first choice for new-build or renovated pools – due simply to its overwhelming advantages over all other technologies. It is also much cheaper to install, operate and maintain than ozone.

UV not only destroys chloramines, the unpleasant by-products of chlorination, but is also a highly effective disinfectant in its own right, which means pool operators can drastically reduce chlorine usage (commonly down to 1.0ppm, or even less). Virtually no microorganisms are immune to UV, even chlorine-resistant pathogens. Another major benefit of UV is that it significantly reduces the need for backwashing and dilution, saving hundreds of pounds a month for pool operators.

Although the need for chlorine is greatly reduced with UV, small amounts are still needed to ensure residual disinfection. Chloramines are formed when free chlorine reacts with sweat or urine in pool water. Trichloramines in particular are powerful irritants which are responsible for eye and respiratory complaints and the unpleasant ‘chlorine smell’ commonly associated with indoor pools. Chloramines are also corrosive and in time can lead to damage to pool buildings and structures such as ventilation ducts. Any water treatment system that reduces reliance on chlorine is therefore welcome.

A typical UV system consists of a UV lamp in a protective quartz sleeve which is mounted within a cylindrical stainless steel chamber. Pool water enters at one end and passes along the entire length of the chamber before exiting at the other end, receiving a dose of UV energy along the way.

Significant cost savings

Pool water currently costs approximately £3 per cubic metre to discharge (taking into account water costs, heating, chemicals and actual discharge costs) and is likely to rise to £4 per cubic metre by 2009, even by conservative estimates. By using UV, which significantly cuts chlorine usage, the requirement for backwashing and dilution is greatly reduced. Even old pools can reduce costs by hundreds of pounds a month by switching to UV, with payback for the initial investment in UV coming within two years. For many pool operators this saving may be the most compelling reason for installing UV.

A link between chloramines and childhood asthma?

A recent study in Belgium appears to confirm earlier research linking chlorine by-products in indoor swimming pools with asthma in children (references 1 & 2). The researchers at the Catholic University of Louvain analysed the rates of wheezing, asthma and other ailments in almost 190,000 13 and 14 year olds in 21 European countries. The results showed rates of asthma and wheezing rose by around 2.7% and 3.39% respectively among regular indoor pool users. In some cases the damage was equivalent to that found in heavy smokers. Even people sitting at the sides of pools, such as lifeguards and instructors, were found to be at risk.

The symptoms are caused, the researchers believe, by chloramines – particularly trichloramines. The problem is potentially so serious that the study’s authors suggested pool operators should seriously consider alternatives to purely chlorine-based disinfection. They also recommended better ventilation to help remove chloramine-laden air from pool surroundings, improved hygiene practices by bathers themselves – such as showering before swimming – and the regular renewal of pool water.

While further research is needed, these findings add further credence to the importance of reducing chloramines as much as possible. Heavy load pools can operate very safely at residual chlorine concentrations of 1.0ppm, while low load pools can easily function at concentrations as low as 0.4ppm if the German DIN standard code is adhered to. Given that combined chlorine will probably be below 0.3ppm, most pool users won’t even be aware that there is any chlorine in the water at all.

Case studies

Cotgrave Leisure Centre, Nottinghamshire
Since opening in 1998, the Cotgrave Leisure Centre near Nottingham has used Hanovia UV to treat the water in its indoor pool. The technology has been so successful that Neil Gallagher, the centre’s Assistant Operations Manager, contacted Hanovia to tell the company how pleased he was.

“I’m really happy the centre decided to install UV right from the start,” said Neil. “We use it for primary disinfection, with 1ppm chlorine added for residual disinfection. We could probably go lower than this, but we prefer to keep it at 1ppm, especially at busy times, as part of our ‘belt and braces’ approach to hygiene.”

Neil added, “With UV, the pool water is much clearer than if we were using chlorine on its own. Also, because UV destroys any chloramines produced by the residual chlorination, the atmosphere around the pool is better, with none of the unwelcome smells or eye irritations normally associated with indoor pools. People often comment on it, and it has even become a bit of a selling point for the pool.”

Dyrons Leisure Centre, Devon
Since Dyrons Leisure Centre in Devon installed a Hanovia UV system, pool water quality has been transformed. The centre has also made significant energy cost savings.

“There has been a real improvement in water quality since we switched to medium pressure UV,” said Engineering Manager Brian Pady. “We have reduced residual chlorination to as little as 0.5 ppm and this reduction in chlorine usage has also resulted in significant cost savings on chemicals. The UV system is also more energy efficient than the old ozone plant, cutting our energy costs by about 30% over two years.”

Comments like these speak for themselves and are a glowing endorsement to the very real benefits of UV.

Conclusion

With many independent schools struggling to keep their swimming pools operational, viable water treatment solutions that don’t break the bank are becoming a necessity. UV is now often the first choice for new-build or refurbished municipal pools, and its overwhelming advantages over all other technologies make it an ideal choice for independent schools as well.

Even though UV significantly reduces reliance on chlorine, residual amounts are still necessary to ensure effective disinfection of pool water. This leads to the production of chloramines, which must be removed if the pool environment is to remain acceptable to bathers. UV systems are particularly suited to both chloramine destruction and disinfection. The resulting effect is a cleaner, more pleasant atmosphere both in and around the pool. The potential asthma side effects caused by trichloramines are significantly reduced, and the danger of infection by harmful microorganisms is also eliminated.

All UV systems are compact and can usually be installed within existing pipework. Automatic wipers keep the quartz sleeves housing the UV lamps clean, so the only regular maintenance required is changing the lamp every nine to twelve months – a simple operation that is carried out by on-site staff. Reduced chlorine usage also results in significant cost savings for the pool operator, as well as cutting down on chemical handling.

References:

1. Bernard, A., et al, (2003). Lung hyperpermeability and asthma prevalence in schoolchildren: unexpected associations with the attendance at indoor chlorinated swimming pools. Occupational & Environmental Medicine, 60, 385-394.

2. Nickmilder, M., and Bernard, A. (2006). Ecological association between childhood asthma and availability of indoor chlorinated swimming pools in Europe. Occupational & Environmental Medicine, July 2006, Volume 63, doi:10.1136/oem.2005.025452.

Comments Off

UV disinfection specialist Hanovia Limited has appointed John Ryan as its new Managing Director. John has over 20 years international experience in the water treatment industry and brings a wealth of expertise and knowledge to the company.

He joins Hanovia from Christ Water Technology, where he served most recently as the  Head of Group Customer Services, and previously as the Managing Director of Christ Water Technology in Ireland. Prior to joining Christ he worked for a number of leading water technology companies, including Veolia, Memcor and Permutit Boby.

John received an MBA from Warwick University and holds a BSc in Chemical Engineering from Loughborough University. He is a Chartered Engineer and a member of the Institution of Chemical Engineers.

“My aim is to build upon Hanovia’s already extensive presence around the world, to get closer to our existing customers and to enter new markets where our world-leading UV technology has a real advantage,” commented John. “We already have an established presence across Europe, Asia, Australasia and North America (through our US sister company Aquionics) which gives us a strong base with which to grow our business.”

Comments Off

Huge improvement in water quality and payback in less than a year

Since installing a Hanovia UV water treatment system, the Lloyd Elsmore Park Leisure Centre in Manukau City, New Zealand, has seen a transformation in water and air quality at its indoor leisure pool, one of New Zealand’s busiest. Running costs are also much less and the UV system has paid for itself in less than a year.

“We installed the Hanovia UV system to control combined chlorine, also known as chloramines,” commented Centre Manager Gary Burr. “Since installation it has been doing its job perfectly – combined chlorine levels have fallen from 1.8ppm to 0.5ppm, resulting in a much improved pool environment. Visitors have really noticed the difference and we are always getting comments about how much nicer the pool is to swim in, with none of the nasty ‘chlorine’ smells and eye irritations normally associated with indoor pools. People find they no longer need to use eye goggles and don’t smell of chlorine when they leave the pool. The water is also much clearer – transmission has shot up from 80% to 95% – from cloudy to clear.”

Continuing, Gary said, “Other benefits include a big reduction in the amount of dilution water required. Before UV we were replacing about 600m3/water per week, just to keep combined chlorine levels down, and this has now fallen to virtually zero – it’s just not necessary any more. All in all, the reduction in costs for new water, discharged water, lost energy and lost chemicals is considerably lower. The UV paid for itself within less than a year, making this a doubly successful story.”

He concluded by saying, “Following the success of the Lloyd Elsmore Park UV installation, Manukau City Council has ordered two more Hanovia UV systems for other leisure facilities with similarly loaded indoor pools. I know for a fact that the Council has also received many more enquiries, based on the success of our installation.”

The UV system unit installed at Lloyd Elsmore Park is a Hanovia medium pressure PSP UV system, which can treat up to 220 m3/hour, based on a UV dose of 60 mJ/cm2. An automatic wiper keeps the sleeve housing the UV lamp clean, so the only regular maintenance required is changing the lamp every nine to twelve months – a simple operation that is carried out by on-site staff. All Hanovia UV disinfection systems are compact and can usually be installed within existing pipework with minimal disruption.

All Hanovia medium pressure UV systems are compact and can usually be installed within existing pipework. Automatic wipers keep the quartz sleeves housing the UV lamps clean, so the only regular maintenance required is changing the lamp, a simple operation that can be done in minutes. Reduced chlorine usage also results in significant cost savings for the pool operator, as well as cutting down on chemical handling.

Comments Off